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PROTO-SPHERA, a new and different magnetic-confinement configuration for Controlled Thermonuclear Fusion.

Alladio F., Micozzi P.
  Venerdì 30/09   15:00 - 18:00   Edificio Psicologia 2 - Aula 2B   II - Fisica della materia
At the C.R. ENEA Frascati Research Center, the PROTO-SPHERA experiment is a new and different magnetic-confinement configuration that attempts to control a thermonuclear fusion plasma. More than twenty years ago it was found that compared to a conventional Tokamak, a Spherical Tokamak improves the ability of the magnetic field to produce a high plasma pressure (from $\beta < 5$% to $\beta \sim 30$%). PROTO-SPHERA purpose is to take maximum advantage of the magnetic field ({\beta $\sim 100$%): namely PROTO-SPHERA is built around a "central column", which is no longer a Spherical Tokamak metal conductor, but it is a "plasma centerpost" Spherical Tokamak, so that the plasma is simply connected: a cylindrical vacuum vessel contains a few metal shielded "poloidal field coil", furthermore there are an annular cathode and an annular anode for the plasma breakdown. Two degenerate $(B$ = 0) X-point of the magnetic field are present on the top and bottom of the plasma, so there are two nozzles: depending on the winding direction of the plasma current, just one nozzle between the two will become the main nozzle for the charged particles produced by thermonuclear fusion. Therefore, if the conditions of nuclear fusion can be realized in the future on magnetic confinement configuration similar to PROTO-SPHERA, it will directly become a spatial thruster a million times more powerful than chemical rockets, per unit mass. Now PROTO-SPHERA cylindrical vacuum vessel contains only eight "poloidal field coil" to create the "plasma centerpost". In 2015 PROTO-SPHERA experiment began creating its first "plasma centerpost". In the second phase of the experiment 10 further "poloidal field coil" will be added, in order to squeeze the plasma, for creating and maintaining around the "plasma centerpost" the spherical tokamak.